c
c a star graph with back-forth edges radiating outwards and inwards
c at least one outer vertex must be green
c center vertex must be blue and only blue
c
p edge 9 16
e 1 2
e 2 1
e 1 3
e 3 1
e 1 4
e 4 1
e 1 5
e 5 1
e 1 6
e 6 1
e 1 7
e 7 1
e 1 8
e 8 1
e 1 9
e 9 1

